problem with :hover

I’m slightly confused at the question, do you just want images to be grayscale on page load and then color when you hover? If thats the case you could add this to your images:

https://css-tricks.com/almanac/properties/f/filter/#article-header-id-1

img {
-webkit-filter: grayscale(1);
filter: grayscale(1);
}

and then remove the grayscale to color on hover.

img:hover {
-webkit-filter: none;
filter: none;
}

Hope that helps some.